Flexible polymer substrates are being developed that incorporate optical and electronic elements. Organic light emitting diodes (OLEDs) and transistor-based electronics are examples of such elements that can be fabricated on flexible polymer substrates. Polymer substrates are attractive due to their being lightweight, impact resistant, and flexible. However, polymer substrates typically have poor barrier properties, making devices fabricated on such substrates vulnerable to oxygen and moisture ingression.
Due to the low barrier performance of polymeric material to moisture and oxygen, polymer substrates need to be protected with a barrier film. As the performance of low permeability barrier films increases, improved techniques are needed to accurately measure relatively low gas and moisture permeation rates for barrier coated polymer substrates.